Laminated ink-jet recording heads have heretofore been known that comprise a nozzle plate, pressure generating compartments and a diaphragm in superposition and which have piezoelectric vibrators of a flexural vibrating mode mounted on a surface of the diaphragm (for example, Unexamined Published, Japanese Patent Application (kohyo) No. Hei 5-504740). Typically, most of the members that constitute the laminated ink-jet recording head are formed of ceramics. Hence, by sintering the aforementioned members in the form of superposed green sheets (claey sheets), those members can be fixed without using an adhesive. The resulting advantage of this feature is that the step of joining the individual layers together can be eliminated to thereby simplify the manufacturing process.
However, with the aforementioned conventional art laminated ink-jet recording head, two operations are necessary, one for superposing the green sheets of the respective members and the other for sintering them. It should here be noted that since the aforementioned respective members are made of ceramics comprising different ingredients, the diaphragm and the piezoelectric vibrator that have different coefficients of thermal expansion are superposed and sintered. Hence, due to the thermal expansion mismatch between the two members, deformation may occur after sintering or warpage and the like may prevent complete joining of the two members.
Under the circumstances, the present inventors conducted intensive studies and obtained a novel finding in that the above-mentioned problems could advantageously be solved by producing piezoelectric vibrating elements utilizing a hydrothermal method (hereunder sometimes referred to as a “hydrothermal synthesis method”). This hydrothermal method has heretofore been generally known since it has been proposed by, for example, Unexamined Published Japanese Patent Application (kokai) Nos. Hei 5-136476, Hei 6-206787, and Hei 6-314821; however, neither of these patents give consideration to the utilization of the hydrothermal method in the manufacture of laminated ink-jet recording heads.